1. Technical Field
The disclosure relates to an air cooling unit included in a Rankine cycle system.
2. Description of the Related Art
As well known by persons having ordinary skill in the art, a Rankine cycle is an idealized cycle of a steam turbine. The Rankine cycle has been studied and developed from old times. In the meantime, as described in Japanese Unexamined Patent Application Publication No. 2013-7370, a waste-heat recovery generator that recovers waste-heat energy discharged from facilities such as factories or incinerators for use in power generation has been studied and developed.
In the waste-heat recovery generator according to Japanese Unexamined Patent Application Publication No. 2013-7370, a heat energy is recovered from a waste heat medium by an evaporator and the recovered heat energy is used to evaporate the working fluid in the Rankine cycle. The evaporated working fluid drives a turbine generator. After the working fluid has driven the turbine generator, the working fluid is cooled and condensed by a water-cooled condenser. The condensed working fluid is fed to the evaporator again by a pump. In this manner, electrical energy is continuously generated from the waste-heat energy. In recent years, attention has been paid to not only large-scale waste-heat recovery generators but also waste-heat recovery generators installable in relatively small facilities.
Japanese Unexamined Patent Application Publication No. 2009-221961 discloses a binary cycle power generating system illustrated in FIG. 9. A heat source fluid 1 is fed to an evaporator 2 and the evaporator 2 heats a working fluid 10 to evaporate the fluid 10. The evaporated working fluid 10 is fed to a steam turbine 4 to drive the steam turbine 4, so that power is generated. The working fluid 10 ejected from the steam turbine 4 is then fed to a condenser 6 through a heat recovery unit 8. The working fluid 10 is cooled by air and condensed into a liquid by the condenser 6. The condensed working fluid 10 is fed again to the evaporator 2 by a pump 7B and heated by the heat source fluid 1. This binary cycle power generating system can recover heat from the heat source fluid 1 and condense the working fluid 10 using air.
In the case where a water-cooled condenser is used, cooling-water generating facilities, such as a cooling tower, have to be provided. In addition, water piping has to be additionally installed between the Rankine cycle system and the cooling-water generating facilities. This installation involves problems such as increases in costs and footprint. An air-cooled condenser is considered to be advantageous to a water-cooled condenser in terms of costs and footprint. The performance of the air-cooled condenser, however, is usually inferior to the performance of the water-cooled condenser. Thus, further improvement in the performance of the air-cooled condenser is expected.